A breath alcohol tester is a device for estimating a blood alcohol content (BAC) of a user by analyzing a sample of the user's breath. Typically, the user exhales into the breath alcohol tester and any ethanol present in the user's breath is oxidized to yield acetic acid and hydrogen at an anode of the breath alcohol tester. Further, the hydrogen reacts with atmospheric oxygen to yield water at a cathode of the breath alcohol tester. This chemical reaction produces an electric current between the anode and the cathode and a sensor (and associated circuitry) within the breath alcohol tester measures the magnitude of the electric current. The breath alcohol tester outputs an approximation (or representation) of the user's BAC based on the measured electric current.
The anode, cathode, sensor, or other components of the breath alcohol tester may be prone to contamination and interference from substances other than breath alcohol. Further, over time, sensor aging, humidity, and contamination can alter the output of the breath alcohol tester. As a result, the breath alcohol tester may require regular calibration checks or recalibration (collectively calibration processes) to ensure that the breath alcohol tester outputs an accurate estimation (or representation) of BAC. Further, even if the breath alcohol tester does not require regular calibration for accuracy, regular calibration and/or calibration checks of the breath alcohol tester may be required to comply with equipment limitations and/or applicable administrative or legal (e.g., Federal, State, and Local) laws and regulations, for example. There may be other factors that cause the need for regular calibration checks or recalibration of the breath alcohol tester.
Calibration of the breath alcohol tester may be performed using a Dry-Gas method, for example, although other calibration methods are contemplated herein. The Dry-Gas method utilizes a calibration standard, which is a precise mixture of alcohol and inert nitrogen available in a portable pressurized canister. The breath alcohol tester is connected to the calibration standard and measures the alcohol content of the calibration standard. The measured alcohol content is compared with the known alcohol content of the calibration standard. The calibration of the breath alcohol tester is adjusted, if necessary, to match the alcohol content of the calibration standard within a desired degree of accuracy (e.g., within (0.005%).
Calibration of the breath alcohol tester may require specially trained users to accurately and consistently calibrate the breath alcohol tester. Further, if the trained users do not perform the calibration regularly, the users may avoid performing the calibration, induce errors in the calibration, and/or forget how to do the calibration and become uncomfortable performing the calibration. Still further, a failure to correctly calibrate the breath alcohol tester (or not calibrate the breath alcohol tester at all) may render the results obtained from the breath alcohol tester invalid.